The advice on here is great: Slow Down, first of all. When I did C25K, I was jogging at a speed slower than what I could have walked briskly; my jogging was more of a boosted walk. Also don't be afraid to breathe through your mouth, but deeply and from your belly though, not shallow panting breaths as the latter will tire you out and give you that "I can't breathe" feeling. With the breathing, I find it helps if you get into a rhythm with your steps; that sort of helps with remembering to breathe. Like butterflyphreek, I also chew gum sometimes as well.

Most important though, slow down, keep your chest up and practice your breathing. Don't worry about speed for now, it will come.